I looked at a lot of different low note arrangements when I was thinking about a new D/G melodeon. This one seemed like the best compromise for the tunes I play.
(push/pull)
G Row: ( / ) (B /C ) (D /F#) (G /A ) (B /C )...
D Row: ( / ) (G /B ) (A /C#) (D /E ) (F#/G )...
That design exercise was put on hold when I decided to buy a G/C melodeon first. The only change from the standard bottom end of the range I made on the G/C was to replace the redundant push G on the C row with an A to match the reversed G and A reeds in the fifth button of the C row (which is a different discussion topic altogether).
C Row: ( / ) (A /B ) (C /D ) (E /F )...
G Row: ( / ) (D /F#) (G /A ) (B /C )...
I left the first button blank too, because the accidentals are yet another discussion topic,